Travelling guide for rock drilling



Feb. 23, 1965 E. D. NORTON 3,

TRAVELLING GUIDE FOR ROCK DRILLING Filed June 15, 1962 EDGAR D.NQRTON United States Patent 3,170,527 TRAVELLING GUIDE FOR ROCK DRHJLING Edgar D. Norton, Bishop, Califi, assignor to Union Carbide Corporation, a corporation of New York Filed June 15, 1962, Ser. No. 202,880 4 Claims. (Cl. 175326) The present invention relates to a device for directionally controlling the travel of a drill bit, during drilling operations, to produce a series of longitudinally parallel and cross-sectionally overlapping drill holes.

The paramount consideration in efficient and economical hard rock mining operations is maximum breakage of rock per pound of explosive utilized. There are numerous factors which influence breakage of rock per pound of explosive includingdiameter of drill holes, spacing of drill holes and the burn velocity, density and strength of explosives in addition to proper timing of the blast. The present invention is primarily concerned with drill patterns and a device for producing drill patterns in such a manner as to maximize the breakage per pound of explosive utilized as well as to permit much more breakage per pound fired.

For the purpose of the following specification and claims several terms are defined. These terms are commonly utilized in the mining industry to describe various mining operations and parameters. A drill pattern is a particular arrangement of drill holes. A round is a collection of holes drilled in a predetermined pattern to cause rock breakage upon blasting. A free face is a plane not necessarily flat which marks an abrupt change from one material to another. For purposes of the present invention the term free face is utilized to indicate a rock-air free face. Generally speaking, in mining operations the term free face has also been utilized to designate an abrupt change from one type rock to another; in this latter use the term free face indicates the point at which compression waves travelling through rock are reflected back as tension waves. The term advance is used to indicate the linear progress made in blasting and/or excavating an opening such as a drift or tunnel during mining operations.

Another term utilized --in mining operations is expansion ratio. Expansion ratio is the ratio of the open, or drilled out area or volume to the area or volume of rock to be broken (i.e. expanded) per round of explosive. In hard rock mining operations it is necessary to blast to a free. face to achieve maximum breakage per pound of powder. There are numerous methods for utilizing an existing free face or for creating a free face. For example, FIG. 5 illustrates a wedge cut wherein the advance face of the drift is utilized as the free face. FIG. 6 illustrates the well known V pattern or cut wherein the free face is again the advance face of a drift. While the wedge and V cuts are operable, they have common shortcomings which are limited advance per round and high waste drill footage per pound of rock breakage. Advance is generally limited to less than the dimensions of the drift or other opening when a wedge or V out pattern is utilized.

Another method of creating a free face consists of drilling holes generally perpendicular to the advance face of an opening. FIGURE 3 illustrates a view in elevation of the advance face showing a number of drill holes. In this method, commonly called the burn method, hole A is the free face and is not loaded with explosives. Surrounding hole A are numerous drill holes which are loaded with powder in any number of patterns. For example, holes E, I, G or D, F, H or K, J, W, M may be loaded and upon blasting the rock breakage is to the free face created by hole A. Due to the relatively small area of the free face created by hole A, the advance per 3,17,527 Patented Feb. 23, 1965 round is small though drill footage per. pound of rock breakage is rather high. In the burn method it would be extremely desirable to have a burn out consisting of longitudinally parallel and cross-sectionally over-lapping holes. It is virtually impossible to drill such a pattern of holes even to a shallow depth in hard rock since drillbit wander cannot be controlled to any great extent. The term wander is used in mining operations generally to indicate the uncontrollable travel of a drill bit in a direction not generally coincident with the longitudinal axis of a drill rod to which the drill bit is attached. Also, drilling such a consistent pattern of cross-sectionally overlapping holes to extensive depths in hard rock cannot be accomplished. In addition, since drill bit wander is diificult to control, successive holes are not drilled parallel and the expansion ratio is low.

The main object of the presentinvention is to provide a device for directionally controlling the travel of a drill bit through rock so as to consistently and continuously produce a series of longitudinally parallel and cross sectionally overlapping drill holes. Other objects include a device adaptable to drilling various drill patterns, providing a free face for blasting operations'in a greatly improved manner, providing a free face which permits much greater breakage per given drill footage and much more efiicient utilization of explosive per pound of rock breakage.

The present invention is especially adaptable for directionally controlling the travel of a drill bit during rock drilling operations so as to produce a series of longitudinally parallel and cross-sectionally overlapping drill holes. The invention includes a travelling guide comprising an elongated guide member longitudinally parallel and fixedly connected to a drill rod sleeve wherein the elongated guide member has a longitudinal axial dimension substantially greater than the longitudinal axial dimension of the drill rod sleeve.

The present invention in addition includes a travelling guide and drill rod assembly comprising a drill rod loosely fitting in a drill rod sleeve, the drill rod sleeve being longitudinally parallel and fixedly connected to an elongated guide member having longitudinal axial dimension substantially greater than the longitudinal axial dimensions of the drill rod sleeve. The drill rod sleeve is slidably positioned on the drill rod near the drill bit. The drill bit is fixedly attached to the end of the drill rod. The drill rod sleeve is positioned between the drill bit and .a drill rod coupling means, thereby restricting the motion of the drill rod sleeve along the longitudinal axis of the drill rod. The motion of the drill rod sleeve is restricted, by drill rod coupling means, to that portion of the drill rod near the drill bit.

FIGURE 1 is an exploded longitudinal view of a travelling guide and drill rod elements constructed in ac- 'cordance with the present invention.

FIGURE 2 is a longitudinal view of the FIGURE 1 embodiment as assembled.

FIGURE 3 is a view of a free face showing a drill hole pattern with the travelling guidedrill rod assembly in working position.

FIGURE 4 is an elevational view of FIGURE 3 taken in cross-section along line 4--4.

FIGURE 5 is a view of a cross-sectional side view of a drill pattern in the advance end of a drift.

, FIGURE 6 is a full view of a cross-sectional to view of another drill pattern in the advance end of a drift.

Referring to FIGURE 1, the travelling guide comprises an elongated guide member 1 longitudinally parallel with and fixedly connected to a drill rod sleeve 3 through a spacer 7. FIGURE 1 also shows, as disassembled, drill rod portions 5 and 6, a coupling means 11 for fixedly attaching drill rods 5 and 6 together, a

drill bit 9 fixedly attached tot he end of drill rod 5 and coil springs 13 and 1-5.

rod sleeve 3, spacer 7 and elongated guide member .1

comprise the travelling guide or the present invention. Drill rod sleeve 3 is positioned between the drill bit .9 and rod coupling means 11. Drill bit and rod coupling means 11 restrict the motion of the travelling guide along the longitudinal axis of drill rod to that motion permitted by the resilience of coilspring 13 and coil spring 15.

In operation, a pilot hole 17 as shown in FIGURE 3 of the, desired length is first drilled into a rock face 4, instances, the detrimental fracturing of the rock shells 19 and 21 can be completely obviated by employing a spacer between the mide member and the drill rod sleeve.

With respect to specific dimensions of the present ap paratus it has been found that for a given drill bit which produces a hole of diameter D, a cylindrical elongated guide member ideally has an outside diameter of about 0.875D, a length of about 13.0D and beveled ends. The

" drill rod sleeve ideally has an outside diameter less than about 0.875D. The drill rod sleeve and the elongated guide member are preferably separated by a spacer ranging in width from about 0.167D to about 0.251).

From the aforementioned disclosure it is readily apparent that the present novel apparatus represents a conutilizing a device comprising a drill rod 5, drill bit 9 and coupling means 11 as shown in FIGURE 1 and means .for rotating the drill rod and bit. The travelling guide is not utilized in drilling pilot hole 17. After the/desired depth of penetration of the pilot hole 17 is reached with the standard device, the drill'rod 5 and/or drill bit 9 is disassembled and the travelling guide assembly is positioned on the drill rod 5 by passing the drill rod 5 through the drill rod sleeve 3. The drill rod 5 and/ or drill bit 9 are then attached to drill rod das shown in FIGURE 2. The elongated guide member 1 is then inserted into the pilot hole 17 and the drill bit is abutted against therock face and rotated to commence drilling another hole.

As drilling continues,elongated guide member 1 advances with the drill bitconstantly and consistently guiding the drill bit by travelling with the ad- Vance of the, drill bit so as to produce longitudinally parallel and cross-sectionally overlapping holes. Once the pilot hole has been drilled, any number of cross-sectionally overlapping holes may subsequently be drilled. FIGURE 3 shows three such holes although any desired number may be drilled. Inaddition, FIGURE 3 shows the. outer-ends of the present apparatus in working position.

Due to the rather high shock and stress on the travelling guide assembly .duringdrilling, it is preferred to restrict the motion of drillrod sleeve 3 along'the drill rod 5 by resilient means. FIGURE 2 shows such an embodiment wherein coil springs 13 and 15 butt up against the guiding sleeve and'restrictits motion along the longitudinal axis of the drill rod to that motion permitted by the resilience of the coil springs.

The relative dimensions of the travelling guide assembly may be altered as desired without departing from the spirit and scope of the present invention. It has been found that the guide member 1 and the drill rod sleeve 3 must move freely through the longitudinally parallel and cross-sectionally overlapping drill holes without being caused to bind on the rockshells 19 and 21 which .are formed during drilling of the two adjacent and circumferentially intersecting holes. In some instances it may be desirable and even necessary to include a spacer such as spacer 7 between the guide member 1 and the drill rod sleeve 3. In these instances it is important that the spacer be of such dimensions, both as-to width and spacing height, as to permit free travel of the travelling guide longitudinally within a prior drilled hole and the intersecting hole being drilled. It should also be noted that siderable contribution to the mining art. Minor modifications may be made in the hereindisclosed invention without departing from the spirit and scope of the presentinvention. A

What is claimed is: e

l. A rock drilling apparatus for directionally controlling the travel of a drill bit when drilling a hole parallel to and intersecting a prior drill hole, said apparatus comprising a travelling guide consisting of a drill rod sleeve being longitudinally parallel and fixedly connected through a spacer to an elongated guide member, said elongated guide member. having cross-sectional dimensions substantially the same as said drill ro'd sleeve and having longitudinal axial dimensions substantially greater than said drill rod sleeve, said spacer having a thickness less than the width of the opening left at the overlapping portion of the drill holes, a drill rod loosely fitting insaid drill rod sleeve, said drill rod sleeve being slidably positioned between a'drill bit fixedly attached to the end of said'drill rodand drill rod coupling means,

. resilient means positioned between said drill bit and one longitudinal extremity of said drill rod sleeve .and between said drill rod coupling means and the other longitudinal extremity of said drill rodrsleeve for restricting the motion of said drill rod sleeve alongthe longitudinal axis of said drill rod close to the drill bitend of said drill rod, said apparatus being suitable for use in producing a series oflongitudinally parallel and cross-sec tio nally overlapping holes.

2. A device in accordance with claim 1 wherein said resilient means comprises. a first coil spring positioned concentric with said drill rod between said drill bit and one longitudinal extremity of said drill rod sleeve 'and a second coil spring positioned between said drill rod coupling means and the other longitudinal extremity of said drill rod sleeve.

3.-A device in accordance with claim 1, wherein said elongated guide member and said drill rod sleeve are cylindricalin shape.

4. A device in accordance withclaim 2 wherein said drill bit produces a hole of diameter .D during operation, said elngated guide memberbeing cylindrical and having an outsidediameter of about 0.875D, a length of about 13.0D and beveled ends, said-drill rod sleeve having an outside diameter less than about 0.875 D and said Id-rill rod sleeve and said elongated guide member being separated by a spacer ranging in width firom about 0.167D to 0.25D.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A ROCK DRILLING APPARATUS FOR DIRECTIONALLY CONTROLLING THE TRAVEL OF A DRILL BIT WHEN DRILLING A HOLE PARALLEL TO AND INTERSECTING A PRIOR DRILL HOLE, SAID APPARATUS COMPRISING A TRAVELLING GUIDE CONSISTING OF A DRILL ROD SLEEVE BEING LONGITUDINALLY PARALLEL AND FIXEDLY CONNECTED THROUGH A SPACER TO AN ELONGATED GUIDE MEMBER, SAID ELONGATED GUIDE MEMBER HAVING CROSS-SECTIONAL DIMENSIONS SUBSTANTIALLY THE SAME AS SAID DRILL ROD SLEEVE AND HAVING LONGITUDINAL AXIAL DIMENSIONS SUBSTANTIALLY GREATER THAN SAID DRILL ROD SLEEVE, SAID SPACER HAVING A THICKNESS LESS THAN THE WIDTH OF THE OPENING LEFT AT THE OVERLAPPING PORTION OF THE DRILL HOLES, A DRILL ROD LOOSELY FITTING IN SAID DRILL ROD SLEEVE, SAID DRILL ROD SLEEVE BEING SLIDABLY POSITIONED BETWEEN A DRILLBIT FIXEDLY ATTACHED TO THE END OF SAID DRILL ROD AND DRILL ROD COUPLING MEANS RESILIENT MEANS POSITIONED BETWEEN SAID DRILL BIT AND ONE LONGITUDINAL EXTREMITY OF SAID DRILL ROD SLEEVE AND BETWEEN SAID DRILL ROD COUPLING MEANS AND THE OTHER LONGITUDINAL EXTREMITY OF SAID DRILL ROD SLEEVE FOR RESTRICTING THE MOTION OF SAID DRILL ROD SLEEVE ALONG THE LONGITUDINAL AXIS OF SAID DRILL ROD CLOSE TO THE DRILL BIT END OF SAID DRILL ROD, SAID APPARATUS BEING SUITABLE FOR USE IN PRODUCING A SERIES OF LONGITUDINALLY PARALLEL AND CROSS-SECTIONALLY OVERLAPPING HOLES. 